An electrophoretic deposition method of forming a boron nitride (BN) nanotube interface coating on ceramic fibers has been developed. The method comprises immersing first and second electrodes in a suspension including surface-modified BN nanotubes, where the first electrode includes ceramic fibers positioned on a surface thereof. The surface-modified BN nanotubes comprise BN nanotubes with an electrically charged polymer adsorbed on surfaces thereof. A voltage is applied to the first and second electrodes, and the surface-modified BN nanotubes move toward the first electrode and deposit on the ceramic fibers. After the deposition of the surface-modified BN nanotubes, the ceramic fibers are removed from the suspension and heat treated. Accordingly, a BN nanotube interface coating is formed on the ceramic fibers.